Apparatus for splicing pairs of arrayed or individual fibers utilizing optical fiber aligning grooves

ABSTRACT

Mating pairs of arrayed optical fibers are axially aligned and abutted preparatory to splicing, by being urged down an inclined guide ramp and into respective fiber receiving grooves. The splice is completed by applying index matching material and a splice connector plate to the abutted joint.

3S0-96a15 s12 United States Patent 1191 Cherin et al.

[4 1 Oct. 14, 1975 [54] APPARATUS FOR SPLICING PAIRS OF ARRAYED ORINDIVIDUAL FIBERS UTILIZING OPTICAL FIBER ALIGNING GROOVES [75]Inventors: Allen Henry Cherin, Doraville;

Philip Jay Rich, Atlanta, both of Ga.

[73] Assignee: Bell Telephone Laboratories,

Incorporated, Murray Hill, NJ.

[22] Filed: Oct. 24, 1974 [21] Appl. No.: 517,420

[52] US. Cl. 156/502; 156/158; 156/296; 156/304; 350/96 B [51] Int. Cl.B6SH 69/06 [58] Field of Search 29/464, 466, 467, 468,

29/474.4, 203 J, 203 P; 156/158, 161, 166, 304, 502, 494, 296, 459, 460;350/96 B, 96 Y c; 65/4 [56] References Cited UNITED STATES PATENTS3,614,415 10/1971 Edelman 350/96 B 3,674,013 7/1972 Polanyl..- 350/96 B3,768,146 lO/l973 Braun et al.... 350/96 B 3,810,802 5/1974 Buhite etal. 156/158 3,864,018 2/1975 Miller 65/4 Primary ExaminerWilliam A.Powell Assistant Examiner-Brian J. Leitten Attorney, Agent, or Firm-C.E. Graves ABSI'RACT Mating pairs of arrayed optical fibers are axiallyaligned and abutted preparatory to splicing, by being urged down aninclined guide ramp and into respective fiber receiving grooves. Thesplice is completed by applying index matching material and a spliceconnector plate to the abutted joint.

7 Claims, 7 Drawing Figures U,S. Patent 00p. 14,1975 Sheet 1 of3APPARATUS FOR SPLICING PAIRS OF ARRAYED OR INDIVIDUAL FIBERS UTILIZINGOPTICAL FIBER ALIGNING GROOVES Background of the Invention Theadvantages-of transmitting informationvia optical fiber lighttransmission medium are widely recog nized in theTelecommunicationsindustry. However, the problem of optical fiber splicing is a majorchallenge .to the maximum development of this valuable medium. s a ISeveral, researchers have already directed their attention to .thisproblem. Examples are D. L. B isbee'in his article entitled, ,iQptical,Fiber Joining Techniques, Bell System Technical Journal, No. 10, Dec.1973, and E. A. J. Marcatili in his article entitled, Research onOptical Fiber Transmissions,. Bell Laborataries Record, Dec. 1971, pages331-338.

. The present invention has one object to efficiently construct low lossoptical fiber splices in a field or plant environment without a minimumof specialized equipment.

Another object of the invention is to take advantage of commerciallyavailable, low-cost materials so as to make optical fiber splicingfeasible in situations'where it may not be otherwise.

SUMMARY OF THE INVENTION Respective ones of one linear arrayof opticalfibers in a ribbon structure may be axially aligned and abutted with therespective ones of an identical second array of optical fibers by usingtwo guide ranges inclined at either end of a surface withfiber-receiving grooves. In one embodiment, pairs of ribbons eachcontaining spaced'optical fibers are placed in opposing ribbon guidegrooves. Each pair of fiber ribbons'is then slid down the ribbon guidegrooves. The individual fibers encounter respective fiber aligninggrooves at a'slight angle, the grooves having the same' center-to-centerspacing as that of the arrayed fibers. Because of the in- 'cline, adownward bias force is generated in each fiber, tending to hold eachfiber snugly in its groove. Axial alignment of the mating fibers is thuspromoted.

The splice is completed by applying index matching material and a spliceconnector plate to the abutted joint. The splicing technique isapplicable to joining of single fibers, or mating fibers in a pair ofribbons, or several pairs of ribbons containing multiple fibers.

Brief Description of the Drawing FIG. 1 is a perspective view of theguide ramp assembly containing the ribbon guide grooves and fiberaligning grooves;

FIG. 2 shows the fiber ribbons being slid into the fiber aligninggrooves;

FIG. 3 is a close-up view of the fibers seated in the fiber aligninggrooves;

FIG. 4 is a perspective view of a completed splice;

FIG. 5 is a perspective view of the guide ramp assembly with expandedcapacity;

FIG. 6 is, a close-up view ofa cross sectionof the thin chip rampassembly; and I FIG. 7'is a perspective view of the thin chip rampassembly.

Detailed Description of Illustrative Embodiments The optical fiberaligning assembly illustrated in no.

1 is intended to join the mating fibers of two fiber rib-, bons. Itconsists of identical guide ramps 1 and Leah having'a slightly inclinedplanar;surface 4 and 5 containing ribbon guide grooves 8, 8a,respectively.

A plate 3 is disposed between the ramps 1, 2 to receive' a plasticsubstrate 6 with parallel fiber aligning grooves 7 along its topsurface. The ends of each guide groove 8, 8 a, lead in at aslight angleto the bottomsurfaces of fiber'aligning grooves 7.

- As shown in FIG; 2; two fiber ribbons 9, 9a each con-- taining-opticalfiber arrays 10, 10a, respectively,'areintroduced into.grooves 8, 8a. ls .1. Y

One of the edges, for example, edge '30 of each guide groove is locatedat the same transverse distance from the centers of the fiberaligninggrooves 7 as the edge of the fiberribbon is from the axes ofthefibers within theribbon. Edge 8a thus becomes a reference surface toassure proper.ihitialtransverse'positioning of the fi-v bers. The fiberribbons 9, 9a are then-slid down, the ribbon guide grooves 8, 8a towardseach other, and the fiber arrays 10, 10a enter into opposing ends of therespective fiber aligning grooves 7. The fibers undergo a slight bend,and the resulting bending stress in each fiber biases that fiberdownwardly and snugly into its groove. The fibers to be mated thus areaxiallyaligned when they enter into the fiber aligning grooves.

The fiber ends are abutted in axial alignment as above,'and the abuttedjoints are then covered with splice connector cover plate 11, shown inFIG. 4. The splice may then be completed as by applying pressure to thesplice connector cover platell to cause it to chemically adhere toplastic substrate 6. Advantageously, plate 11 may be positioned andadhered to the plastic substrate, 6 in one operation by placing theplate 11 in a cover plate holder 13 which is attached to embossing head14 as illustratedin FIG. 4. In all cases, an index matching materialshould be placed between each pair of abutted fiber ends.

The fiber aligning grooves 7 may be pre-engraved, pre-embossed, orembossed while positioned on the ramp connector'plate 3 by use ofembossing head 14 shown in FIG. 4. I Y

The basic principle of this invention may be extended I so that severalpairs of ribbonsare spliced in one operation, for example asillustratedin FIG. 5. The components include guide ramps la, 2a whichhave multiple guide grooves 812, 8c, served by multiple sets offiberreceiving grooves 7. The method of use is similar to that describedwith respect to FIG. 2.

Arrayed optical fibers may also be spliced in accordance with theteachings of this invention by using a unitary thin chip 20 illustratedin FIG. 7. The top surfaces of the chip 20 are slightly inclined oneither side of the center portion with respect to the center, creatingtwo fiber ribbon lead-in ramps functionally the same as those of FIG. 5.The chip 20 includes parallel ribbon guide grooves 8a, 8b. Each pair ofopposing grooves 8b, 80, lead into a center position 21 which includesseveral equally spaced flber aligning grooves 7, a close-up view ofwhich is illustrated in FIG. 6.

Pairs of fiber ribbons 9 are placed in respective opposing ends ofribbon guide grooves 8. The fibers are abutted and spliced in accordancewith the procedure already stated above, except in this case the rampportions become a permanent part of the completed splice. The embodimentinvolving thin chip 20 has the additional advantage of being relativelyinexpensive, since it may be constructed inexpensively as by injectionmolding.

Pursuant to the most elemental inventive embodiment, a single pair ofoptical fibers may be abutted and spliced in accordance with theteachings of this invention. For example, fiber ribbon 9 illustrated inFIG. 2 may be constructed so as to contain a single fiber, in which casea single pair of fibers could be abutted and spliced pursuant to theabove-stated procedure. Or, a single 'pair of fibers may be fed directlyinto opposing ends of a single fiber aligning groove 7, ofthe apparatusdepicted in FIG. 7, guidedby manual means.

In all cases, a downward stress should be maintained on the fiber ends10 as they are entered, at a slight angle, into the fiber aligninggrooves 7 so as to cause the fibers 10 to be biased along the bottom ofthe fiber aligning groove 7 and into abutment, and kept in that positionuntil the splice is completed.

lt is to be understood that the embodiments desdribed herein are merelyillustrative of the principles of the invention. Various modificationsmay be made thereto by persons skilled in the art without departing fromthe spirit and scope of the invention.

What is claimed is:

1. Apparatus for joining optical fibers ofa first linear array in axialalignment with corresponding fibers of a second linear array comprising:

a surface comprising parallel fiber-aligning grooves having the samecenter-to-center spacing as the fibers of said arrays;

means for advancing the fibers of said first and said second arrays intotheir respective said grooves toward each other and at a small acuteangle with respect to the grooves, thus to generate within each saidfiber a downwardly biasing stress when each said fiber contacts its saidgroove;

said biasing stress maintaining each said fiber in contact with its saidgroove, the ends of respective corresponding fibers meeting in opposingaxial alignment, and

means for securing said fibers in said axial alignment.

- 2. Apparatus pursuant to claim 1 wherein said linear having at leastone fiber-locating edge; and said advancing means comprises a ramphaving a flat floor with an associated guide surface against which saidribbon edge abuts for laterally positioning the fibers of each saidarray with respect to said grooves.

3. Apparatus pursuant to claim 2, further comprising a flat-surfacedpanel recessed below and connecting the ends of said ramps; and a thinchip containing said grooves placed in said recess atop said panel andoriented to receive said advancing fibers.

4. Apparatus for joining a plurality of first linear arrays of opticalfibers with a like plurality of second linear arrays of optical fiberscomprising:

a surface containing parallel fiber alignment grooves arranged in pluralgroups, each said group of grooves designed to receive a selected pairof fiber arrays to be joined;

means for advancing the selected fiber arrays to be joined into theirrespective grooves, with the fiber axes slightly inclined to the groovesin amounts sufficient to generate within each said fiber a downwardlybiasing stress after each said fiber contacts its said groove; 7

the ends of respective corresponding fibers meeting in abutting coaxialalignment; and 7 means for securingsaid fibers in said axial alignment.

5. The apparatus described in claim 4, fabricated as a one-piece unitarystructure.

6. Apparatus pursuant to claim 5, wherein said linear arrays eachcomprise fibers contained in a ribbon structure having at least onefiber-locating edge; and each said advancing means comprises a ramphaving a flat floor with an associated guide surface against which aribbon edge abuts for laterally positioning the fibers of each saidarray with respect to their said grooves.

7. Apparatus for joining a first optical fiber to a second opticalfiber, comprising: 7

a surface having a fiber aligning groove; and

means for advancing said first and said second fibers into said groovetoward each other and at a small angle of inclination with respect tothe longitudinal direction of said groove thus to generate within eachfiber a downwardly biasing stress after each said fiber contacts saidgroove;

said stress causing each said fiber to stay in contacting engagementwith said groove;

the ends of said first and said second fibers meeting in abutting axialalignment.

arrays comprise fibers contained in a ribbon structure 4 1 v a I I

1. APPARATUS FOR JOINING OPTICAL FIBERS OF A FIRST LINEAR ARRAY IN AXIALALIGNMENT WITH CORRESPONDING FIBERS OF A SECOND LINEAR ARRAY COMPRISING:A SURFACE COMPRISING PARALLEL FIBER-ALIGNING GROOVES HAVING THE SAMECENTER-TO-CENTER SPACING AS THE FIBERS OF SAID ARRAYS, MEANS FORADVANCING THE FIBERS OF SAID FIRST AND SAID SECOND ARRAYS INTO THEIRRESPECTIVE SAID GROOVES TOWARD EACH OTHER AND AT A SMALL ACUTE ANGLEWITH RESPECT TO THE GROOVES, THUS TO GENERATE WITHIN EACH SAID FIBER ADOWNWARDLY BIASING STRESS WHEN EACH SAID FIBER CONTACTS ITTS SAIDGROOVE, SAID BIASING STRESS MAINTAINING EACH SAID FIBER IN CONTACT WITHITS SAID GROOVE, THE ENDS OF RESPECTIVE CORRESPONDING FIBERS MEETING INOPPOSITE AXIAL ALIGNMENT, AND MEANS FOR SECURING SAID FIBERS IN SAIDAXIAL ALIGNMENT.
 2. Apparatus pursuant to claim 1 wherein said lineararrays comprise fibers contained in a ribbon structure having at leastone fiber-locating edge; and said advancing means comprises a ramphaving a flat floor with an associated guide surface against which saidribbon edge abuts for laterally positioning the fibers of each saidarray with respect to said grooves.
 3. Apparatus pursuant to claim 2,further comprising a flat-surfaced panel recessed below and connectingthe ends of said ramps; and a thin chip containing said grooves placedin said recess atop said panel and oriented to receive said advancingfibers.
 4. Apparatus for joining a plurality of first linear arrays ofoptical fibers with a like plurality of second linear arrays of opticalfibers comprising: a surface containing parallel fiber alignment groovesarranged in plural groups, each said group of grooves designed toreceive a selected pair of fiber arrays to be joined; means foradvancing the selected fiber arrays to be joined into their respectivegrooves, with the fiber axes slightly inclined to the grooves in amountssufficient to generate within each said fiber a downwardly biasingstress after each said fiber contacts its said groove; the ends ofrespective corresponding fibers meeting in abutting coaxial alignment;and means for securing said fibers in said axial alignment.
 5. Theapparatus described in claim 4, fabricated as a one-piece unitarystructure.
 6. Apparatus pursuant to claim 5, wherein said linear arrayseach comprise fibers contained in a ribbon structure having at least onefiber-locating edge; and each said advancing means comprises a ramphaving a flat floor with an associated guide surface against which aribbon edge abuts for laterally positioning the fibers of each saidarray with respect to their said grooves.
 7. Apparatus for joining afirst optical fiber to a second optical fiber, comprising: a surfacehaving a fiber aligning groove; and means for adVancing said first andsaid second fibers into said groove toward each other and at a smallangle of inclination with respect to the longitudinal direction of saidgroove thus to generate within each fiber a downwardly biasing stressafter each said fiber contacts said groove; said stress causing eachsaid fiber to stay in contacting engagement with said groove; the endsof said first and said second fibers meeting in abutting axialalignment.